JP5921841B2 - Tool holder - Google Patents

Description

  The present invention is a tool holder attached to a spindle of a machine tool such as a turning center or a machining center, and suppresses a tool maximum moment and an inertia moment as low as possible. The present invention relates to a tool holder with higher efficiency machining.

  This type of tool holder, for example, will be described with reference to FIGS. 1 and 2a showing an embodiment of the present invention, and constitutes a shank portion 10 having a manipulator portion 11 and a chuck portion for holding a cutting tool of the chuck. It consists of a chuck part 30 and an intermediate part 20 that forms the remainder of the chuck that forms between the shank part 10 and the chuck part 30.

  On the other hand, a machine tool such as a machining center automatically replaces a cutting tool in accordance with each processing step, and the cutting tool is replaced by exchanging a tool holder having a required cutting tool. An apparatus (automatic tool changer (ATC)) that automatically changes the tool (tool holder) places a limit on the size of the tool holder in order to smoothly change the tool holder. For example, as shown in Table 1, the maximum value is determined for each item including mass. Here, in FIG. 2a, tool holder maximum diameter: outer diameter of manipulator part 11, tool maximum length: length from the upper end of shank part 10 to the lower end of chuck part 30, tool maximum moment: upper surface of manipulator part 11 The distance M from the spindle reference plane) to the center of gravity G is multiplied by the mass.

  In the tool holder used for such ATC, the maximum tool length and the maximum mass are naturally within the limits, and the maximum tool moment is also an important factor. This is because if the tool maximum moment exceeds the limit, the tool holder may be thrown out by centrifugal force during tool replacement. In order to improve productivity (workability), it is also important to shorten the non-machining time such as tool change. The larger the maximum mass and the tool maximum moment, the slower the ATC change time. For example, when the mass is 12 kg, the change time is 1.9 seconds, whereas when the mass is 35 kg, the machining mode must be slowed to 4.8 seconds to prevent the tool holder from being thrown out.

  Furthermore, since the main shaft reaches the set rotational speed in several seconds (for example, about 4 to 5 seconds for 8000 rotations and about 1.5 seconds for 4000 rotations) and is the same when stopped, the main shaft rotates at high speed. A large moment of inertia acts on the tool holder attached to the. As this moment of inertia increases, energy consumption increases and the environmental load increases.

  Also, when machining workpieces (workpieces) with high efficiency, the feed rate is increased as much as possible in the linear machining part to increase the amount of cutting removal, and at the corners and curve parts, acceleration / deceleration is quickly applied to perform smooth machining. Is required. The feed rate is obtained by multiplying the rotational speed, the feed amount per blade, and the number of blades. Generally, the feed rate of one blade is adjusted to set a smooth and highly efficient feed rate. For example, at the corner, the cutting area of the tool increases sharply, so by reducing the feed amount of one blade, the load on the tool is reduced, and there is a method to prevent surface defects and blade breakage due to chatter. Yes.

Thus, in high-efficiency cutting, rapid acceleration / deceleration is performed, and a large inertial force is always acting on the tool holder. Similarly to the moment of inertia, the greater the mass and the longer the tool length, the greater the spindle is subjected to inertial force.
For this reason, in a corner portion where acceleration / deceleration greatly works, a tool holder with a large inertial force (for example, a large mass, a distance from the spindle reference plane to the center of gravity of the tool holder, etc.), the tool holder is easily bent, and the tool holder When it bends, the cutting tool bites into the workpiece. This biting causes the workpiece to become defective due to excessive cutting or the like, or the cutting tool is broken. From these facts, at the time of cutting, the tool holder becomes more stable as the inertial force is smaller, which is reflected in high-efficiency machining.

By the way, due to the advancement of technology in recent years, there are an increasing number of difficult-to-cut material processed parts such as aluminum alloy parts and titanium alloys in the aerospace and motor related fields. For example, aluminum structural parts such as aircraft frames, wing ribs and bulkheads, titanium frame parts such as frame components, edge frames, and motor blades and impellers.
Machine tools that process these difficult-to-cut materials with high efficiency, in the case of aluminum processing, the rotational speed reaches 30000 rpm, the feed speed reaches 30000 mm / min (X, Y axes) or more, the spindle motor output Is 80 kW (100 hp) or more, and in the case of titanium processing, there are some that have a main shaft torque of 1500 Nm, and those that bear these are commercialized.

In the machining method, a conventional machining center having three axes (up / down, left / right, and front / rear axis movement) has poor machining efficiency, and a five-axis control machining center in which a rotation axis (A axis, B axis) is added to the three axes. Increasing use cases.
When machining the above-mentioned difficult-to-cut materials with this multi-axis machining center, especially in high-efficiency machining of difficult-to-cut materials with a 5-axis controlled machining center, the spindle has high torque, and the standard spindle taper used in conventional large machines A standard (for example, ISO standard, HSK-A125, etc.) that is slightly larger than the standard is adopted. For this reason, the tool holder mounted on the spindle is also slightly larger than the conventional one in accordance with the standard.

The tool holder HSK shank that conforms to the standard is a new tool adopted in the DIN standard in 1993, and is an acronym for Hohl Schaft Kegel (hollow shank taper) in German. Compared with the 24 taper shank, it has the following features (1) to (5).
(1) It has high static and dynamic rigidity that can obtain extremely high rigidity by radial and axial clamping force due to two-sided restraint.
(2) Since the taper surface and the entire end surface are fixed so that strong frictional adhesion occurs, high torque transmission and accurate positioning (ATC repeatability) can be realized.
(3) By increasing the rotational speed, the tightening force of the wedge-shaped tightening mechanism becomes stronger, and it has high-speed machining performance that does not produce radial clearance.
(4) Since the shank length is about 1/3 of the conventional 7/24 taper shank and the weight is about 1/2, the tool change time is shortened.
(5) Sufficient performance required for practical high-speed and high-precision machining such as coolant supply.

By adopting a large tool holder having an HSK shank having such characteristics, the rigidity of the tool holder itself is remarkably improved, but on the other hand, its mass is significantly increased. For example, it may exceed 15 kg, and it is dangerous for a person to lift up and perform various operations.
As a measure of the mass of the tool holder, a tool holder of BT50 (JIS standard) conforming to the taper standard that is most often used in large machines can be considered, and the maximum is about 10 kg. Further, the mass of a tool holder that holds a frequently used end mill type tool is 10 kg or less.
From such a situation, it is desirable that the tool holder having the HSK shank is as light as possible.

  Further, in this type of tool holder, in recent years, it has been desired that the cutting tool A be grasped with high precision and rigidity by increasing the torque of the spindle, and that the performance of rotation balance and the like should be enhanced and heavy. As a means for satisfying the demand for higher efficiency by cutting, a technique in which a cutting tool is mounted on the chuck portion 30 by a shrink-fit method has been attracting attention (see Patent Documents 2 and 3).

Furthermore, on the production side of the tool holder, the tool holder body is usually manufactured from a steel bar material (straight bar material) considering the machining allowance to the maximum outer diameter of the tool holder, to the outer peripheral surface shape such as a shank member. Sharpen out. For this reason, the material utilization ratio (size of the tool holder / size of the bar material) of the conventional tool holder is about 1/3, and the remaining 2/3 becomes waste as waste. This waste is a large environmental load. Furthermore, in order to process large parts with high efficiency, a tool holder corresponding to many types of cutting tools is required, and in order to form a system corresponding to these cutting tools, usually about 300 types of tool holders are required. Need to prepare.
It would be desirable to be able to provide a tool holder with sufficient items while avoiding such material waste and minimizing the environmental burden in production.
Incidentally, it goes without saying that, from the viewpoint of cutting, it must be a tool holder that has mechanical strength and bending rigidity that can withstand the ability of a high torque spindle and can contribute to machining efficiency.

Under such circumstances, the weight of the tool holder is reduced, and the chuck (tool holding part) and the shank are separated from each other, and a thin wall with sufficient bending strength is left on both members. There exists what formed the big hollow part (refer patent document 1 summary, FIG. 1).
In addition, the shank and chuck of the tool holder are separated, and the shank and chuck members can be joined to each other, and various shapes can be used to increase the productivity of diversifying tool holders and shorten the delivery time. (See Patent Document 2, paragraph 0013, FIG. 1).
Further, a technique is disclosed in which the outer peripheral surface of the chuck is a concave arc-shaped surface that gradually decreases in diameter toward the tip, and the chuck is divided into a plurality of axial directions (see paragraph 0015 of FIG. 5 and FIG. 5).

JP 2001-252841 A JP 2002-120115 A JP 2009-45716 A JP-A-10-504

  Patent Document 1 FIG. 1 and the like describe that the shank portion and the chuck portion have a hollow structure to reduce the weight, but friction welding is employed for joining the two. In addition, regarding the thin wall thickness of the shank portion, it is only specified as about 10% of the diameter of the maximum diameter portion. Further, the chuck portion is only described as being thin enough to obtain bending strength, and does not provide any indication of how much bending rigidity is related to hollow thin thickness and solid (solid). For this reason, in the description of this document 1, it is not possible to obtain a sufficient cutting ability, and it is not possible to make it easy to apply to heavy cutting of the above difficult-to-cut material only by reducing the weight. In particular, when a shank attached to a high torque main shaft such as the above-mentioned HSK shank is adopted, the chuck also becomes large, and the optimum shape when the weight is reduced by the hollow structure cannot be easily obtained.

Patent Document 3 describes that the chuck is divided into a plurality of axial directions, but does not describe where the division position is.
Furthermore, there is no tool holder in Patent Document 1 or the like that has been reduced in weight considering the maximum tool moment.

In view of the above points, the present invention has a first object to reduce the mass in order to suppress the tool maximum moment, the moment of inertia and the inertial force as low as possible while suppressing the decrease in mechanical strength and bending rigidity. Next, keeping the position of the center of gravity low is a second problem, and a mechanism (configuration) that facilitates weight reduction is a third problem.

  In order to achieve the first object, the present invention provides a tool holder shown in FIG. 1 (a) in which the intermediate portion 20 that forms the remainder of the chuck that is formed between the shank portion 10 and the chuck portion 30 is hollow. In addition, the outer peripheral surface 20 ′ of the intermediate portion 20 and the outer peripheral surface 30 ′ of the chuck portion 30 are tapered so that the diameter gradually decreases toward the tip of the chuck, and the inner peripheral surface 24 of the intermediate portion 20 is also formed. The shape is along the outer peripheral surface 20 '.

  For example, if the shank portion 10 is a shank or a high-speed rotation main shaft mounted on a high torque main shaft of 300 Nm or more, the size of the shank portion 10 is automatically determined, and the chuck portion 30 is a part to which a cutting tool is attached (chucked). Therefore, the thickness and length are automatically determined. On the other hand, the intermediate part 20 between the shank part 10 and the chuck part 30, that is, the remaining part of the chucks of the both parts, can take an arbitrary axial length even if the shank part 10 and the chuck part 30 have the same size. be able to. For this reason, if an intermediate part is made into arbitrary length, the tool holder of arbitrary length (arbitrary cutting depth) can be obtained.

At that time, if the intermediate portion 20 is hollow, the mass of the tool holder is suppressed as much as possible. Further, if the outer peripheral surface of the chuck has a shape that gradually decreases in diameter toward the tip, as shown in FIG. Can be high. At this time, as described in the literature 3, the outer peripheral surface of the chuck is gradually reduced in diameter from the shank to the tip, and is recessed from the tip to the shank over the entire length of the required length. If it is an isolated surface, it can be made more rigid while avoiding interference with the workpiece.
The outer peripheral surfaces of the chuck part and the intermediate part only need to have a shape that gradually decreases in diameter toward the tip, not to mention a beautiful arc or straight taper shape that continues over the entire length, and the arc and straight line A mixed stepwise reduced diameter shape may be used.

Further, if the inner peripheral surface of the hollow portion of the intermediate portion is shaped along the outer peripheral surface, the rotation balance is good. At this time, the inclination degree of the inner peripheral surface of the intermediate portion can be the same inclination degree as that of the outer peripheral surface, for example, the same curvature (parallel), or a shape along the steps (approximate shape).
Further, the inner peripheral surface of the intermediate portion gradually decreases in diameter toward the tip of the chuck in the same manner as the outer peripheral surface thereof, which has an effect that the coolant smoothly flows to the tip (cutting tool) due to the throttle effect of the flow.

  As a configuration of the present invention, a tool holder mounted on the main shaft of a machine tool with the shank is provided with a chuck whose outer peripheral surface is gradually reduced in diameter toward the tip on the shank. A shank portion constituting the shank, a chuck portion constituting a chuck portion for holding a cutting tool of the chuck, and a hollow intermediate portion constituting the remaining portion of the chuck constituting between the shank portion and the chuck portion. In order to reduce the maximum tool moment, inertia moment and inertia force, the outer peripheral surface of the intermediate portion and the outer peripheral surface of the chuck portion are tapered so that the diameter gradually decreases toward the tip of the chuck. A configuration in which the hollow inner peripheral surface of the intermediate portion has a shape along the outer peripheral surface can be employed.

Since the tool holder having this configuration has a large outer diameter and a large second moment of section, the rigidity can be ensured even if the chuck is hollow without making the entire chuck solid compared to a holder with a small diameter. That is, the weight can be reduced without causing a large decrease in rigidity. At this time, the thickness of the intermediate portion may be the same over the entire length in the length direction, but gradually becomes thinner from the shank portion side toward the chuck portion side (the outer peripheral surface and the inner peripheral surface of the intermediate portion). The thickness is preferably gradually increased from the chuck part side toward the shank part side) . This is because the larger the diameter, the greater the rotational torque, so that rigidity is required. If the shank part is thick, the moment of inertia of the cross section is increased and the rigidity is increased.

In the tool holder having this configuration, for example, a frustoconical chuck whose outer peripheral surface is gradually reduced in diameter toward the tip is provided on the same shaft as shown in FIGS. 1A and 1B, and the holder length L is 400 mm. In a tool holder having the same outer shape with a manipulator part diameter D of 125 mm and a chuck member tip outer diameter d of 26 mm, the hollow tool holder A (FIG. 5A) in which the intermediate part 20 is hollow and the intermediate part 20 are solid. In the case of the solid tool holder B ((b) in the figure), the mass (kg), the gravity center position M (mm), the tool maximum moment (= mass × M (kg · m)), the inertia moment (kg · m) ² and XY directions) are as shown in Table 2 below. At this time, M is the distance from the spindle reference plane to the center of gravity G. The shorter the M and the lighter the mass, the smaller the tool maximum moment and the moment of inertia. Incidentally, the center of gravity shifts (becomes lower) toward the bottom surface (shank) in the order of cylinder, cone, and curved cone.

From Table 2, the hollow tool holder A has a mass value that is nearly 30% lower than that of the solid tool holder B, which means that the energy consumption (material) is as low as 30%. , Leading to a reduction in environmental impact. In addition to the mass, the distance M to the center of gravity is also about 6% lower, and the fact that this mass is small and the position of the center of gravity from the spindle reference plane is close (short) reduces the inertial force. Since they are connected, the tool holder is difficult to bend during processing, and the possibility that the cutting tool bites into the workpiece is reduced, the tool holder is stable, and high-efficiency processing is possible.
Further, the hollow tool holder A has a tool maximum moment that is nearly 35% lower, and even when used in an ATC, the centrifugal force during tool replacement is small, and the replacement time can be shortened. Further, since the tool maximum moment is low, the moment of inertia is similarly about 30% lower.
If the outer peripheral surface of the chuck is gradually reduced in diameter from the shank toward the tip, the center of gravity G approaches the main shaft reference surface, and the intermediate portion 20 is made hollow from the comparison of FIG. 1A and FIG. By doing so, the position of the center of gravity G approaches the main axis reference plane, so that the second problem can be achieved.

To achieve the above third object, the present invention is the shank portion, the intermediate portion and the chuck portion, the shank member is a separate member, respectively, consist of the intermediate member and the chuck member, the intermediate member and its shank member A configuration in which the intermediate member and the chuck member are joined via a welded portion is employed.
Thus, the following hollow part can be easily formed by using three members (three pieces) of the shank member, the chuck member, and the intermediate member. In particular, in the case of a shank attached to a high torque main shaft such as an HSK shank, the tool holder becomes large, and it is effective that its hollowing is easy. In addition, by using three members, steel bar material (straight bar material) considering the machining allowance for each maximum outer diameter of each member is used individually, so that the outer peripheral cutting amount can be reduced to three members. This can be reduced compared to the case of manufacturing from one bar material of the same diameter. That is, the amount of chips is reduced and the environmental load can be reduced. The intermediate member can be further divided into two parts, three parts, etc. in the length direction. Thus, unlike the chuck division described in Patent Document 3, the intermediate member division position is specified, and this intermediate member is made to be an extension portion (length adjusting portion) of the tool holder.

  Further, since the intermediate portion constitutes a part of the conventional chuck, the chuck is divided into two parts and the divided members are each processed to be hollow as compared with the case where the chuck is hollow (in the case of a cylindrical shape). If so, the processing work becomes easy and it becomes easy to ensure accuracy.

The welding is because the shank member, the intermediate member, and the chuck member are easy to firmly join each other on the same axis with rigidity. Each member is joined by electron beam welding after being machined and heat-treated. To do.
The electron beam welding has an advantage that strong joining and mass productivity are possible, and has high accuracy in joining each of the shank member and the intermediate member, the intermediate member and the chuck member, and the intermediate member and the chuck with respect to the shank member axis. Joints on the same axis with very little eccentricity and inclination of the members are possible. In addition, since electron beam welding is extremely local welding, unlike TIG welding, preheating and post-heating processes are not required, and machining (cutting, etc.) of the shank member, intermediate member and chuck member → welding of each member → There is also an advantage that the machining (finishing process, etc.) of each member and each process can proceed smoothly.
By this joining, the outer peripheral surface of the intermediate member and the outer peripheral surface of the chuck member are tapered so that the diameter gradually decreases toward the chuck tip.
In addition, since the flexible combination of a shank member, an intermediate member, and a chuck member can be performed freely by the technical force of electron beam welding, these members can be easily integrated.

In this configuration, the above-mentioned HSK shank is effective for reducing the weight of the shank. Further, if the cutting tool is mounted by shrink fitting, the cutting tool can be accurately adjusted as described in paragraphs 0003 and 0004 of Patent Document 3. As well as being firmly grasped and rigid, it can cope with advanced performance such as rotation balance and the diameter of the chuck can be reduced. ) Can be shortened as much as possible, and the rigidity, which is the strength that can withstand the cutting load applied during cutting of the cutting tool, can be increased.
Moreover, when dividing | segmenting, it is preferable that the joining end surface of a shank member and an intermediate member and the joining end surface of an intermediate member and a chuck member are respectively made the same magnitude | size.
If each joining end face has the same size, the deviation in mass and the like at the joining portion is minimized, the rotation balance is good, and the maximum joining strength can be obtained with the minimum joining area. Further, the outer peripheral surfaces of the chuck member and the intermediate member are continuous at the joint (line).

Further, by using the material, for example, carburized steel of the shank member, such as a (SCM415, etc.), if having a hardened layer provide Reinforced curing treatment by carburizing, etc. on the inner peripheral surface (surface only) that, for example, HRC55 If it is about 0 °, the inside of each member (other than the inner and outer surfaces) is close to raw material and has toughness, and mechanical strength comparable to solid (solid) can be obtained. In particular, since the intermediate member has a large hollow portion due to weight reduction as compared with the chuck member or the like, it is preferable to have toughness.
The same material may be used for the shank member, the intermediate member, and the chuck member, but by using different materials for each member, or by forming the joint portion between the shank member and the intermediate member on the inner peripheral surface and the outer peripheral surface, The anti-vibration effect can be enhanced.

  Since the present invention is configured as described above, the tool holder can be reduced in weight by suppressing the tool maximum moment, inertia moment and inertia force as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS The point which is excellent in this invention is demonstrated, Comprising: (a) is a partial cutting front view of a hollow tool holder, (b) is a partial cutting front view of a solid tool holder Partially cut front view of one embodiment of the present invention Partially cut front view of the other embodiment It is operation | movement explanatory drawing of the same embodiment and a comparative example, (a) is an embodiment example, (b)-(d) is each comparative example. It is operation | movement explanatory drawing of the other embodiment and a comparative example, (a) is an embodiment example, (b)-(d) is each comparative example. Corresponding diagram of various chuck members with respect to each intermediate member of the same embodiment

An embodiment of the present invention is shown in FIGS. 2a and 2b, and the tool holder of this embodiment is attached to a main spindle to which a high torque of 300 Nm or more of a machine tool is applied, and is detachably fitted to the main spindle. A chrome molybdenum steel comprising a shank member 10 having a shank of HKS-A125, a truncated cone-shaped intermediate member 20 continuous to the shank member 10, and a truncated cone-shaped chuck member 30 continuing to the intermediate member 20. Made of special steel and special stainless steel.
In the embodiment of FIG. 2a, the holder length L is 285 mm, the diameter c of the joint surface between the shank member 10 and the intermediate member 20 is 94 mm, the intermediate member length a is 165 mm, the chuck member length b is 70 mm, and the chuck member tip outer diameter. d: 15 mm, mounting hole diameter (tool diameter) e: 12 mm, in the embodiment of FIG. 2 b, the holder length L: 285 mm, the diameter c of the joining surface between the shank member 10 and the intermediate member 20 c: 98 mm, the intermediate member length a 165 mm, chuck member length b: 70 mm, chuck member tip outer diameter d: 26 mm, mounting hole diameter e: 20 mm (see FIG. 2a for L, c, a, b, d, and e).

The shank member 10 has a manipulator part 11 on the joint side with the intermediate member 20, and from the curved surface 11a step end face of the manipulator part 11 (position 50mm from the shank side end face of the manipulator part 11, the base point of the intermediate member length a). The outer peripheral surfaces 20 ′ and 30 ′ of the intermediate member 20 and the chuck member 30 are y = ax ² + bx + c, where y is a distance from the holder central axis o, and x is a distance from the stepped end surface to the tip of the chuck member 30. An arcuate surface of a quadratic curve according to (a, b, and c are coefficients) was used. In the figure, 12 is a coolant duct.

The intermediate member 20 has a flange 21 that fits on the inner surface of the end of the manipulator 11 at one end, and a receiving port 22 that fits the flange 31 of the chuck member 30 on the other end. In addition, the inner peripheral surface 24 has two steps of inclined surfaces 24a and 24b and has a shape along the outer peripheral surface 20 ', and its thickness t is from the shank member 10 side toward the chuck member 30 side. As a result, the thickness is gradually reduced to ensure sufficient rigidity. The number of steps of the inclined surfaces 24a and 24b of the inner peripheral surface 24 is arbitrary, and may be a continuous arc shape, for example, an arc shape parallel to the outer peripheral surface 20 ′.
The chuck member 30 has an attachment hole 32 for the cutting tool A formed on the axis from the tip thereof, and a cavity 33 having the same diameter is formed following the attachment hole 32 with a step. The cavity 33 may have a truncated cone shape that gradually increases in diameter toward the intermediate member 20. The cutting tool A is mounted in the mounting hole 32 by shrink fitting.
The intermediate member 20 and the chuck member 30 have a point-symmetric cross section (horizontal cross section in FIGS. 2a and 2b) centered on the central axis o so that rotation unevenness does not occur.

The joining end surface of the shank member 10 and the intermediate member 20 and the joining end surface of the intermediate member 20 and the chuck member 30 are the same size, and when joined, the outer peripheral surfaces 20 ′ and 30 ′ are continuous (in the joining portion). It has an arcuate surface with no step. The shank member 10 and the intermediate member 20 are washed and degreased, and then the intermediate member (special steel) 20 is press-fitted into the joint surface of the shank member 10, and the entire circumference of the joint is electron beam welded. By welding. On the other hand, the intermediate member 20 and the chuck member 30 are similarly cleaned and degreased, and then a special stainless steel neck is press-fitted into the joint surface of the intermediate member, and the entire circumference of the joint is electron beam welded. By welding. By these welding joints, the shank member 10 and the intermediate member 20, and the intermediate member 20 and the chuck member 30 are joined through the welded portions.

Next, as shown in FIG. 3, the tool holder H ₁ (FIG. 2A) of the embodiment of FIG. 2a and the solid shape in which the shank and the chuck are manufactured from one bar material in the outer shape of the tool holder H ₁ . Tool holder H ₂ (same figure (b)), same weight as tool holder H ₁ , tool holder H ₃ of the truncated cone-shaped solid chuck with the shank of HSK-A125 (same figure (c)), and Conventional BT50 type tool holders H ₄ (FIG. 4D) were produced. Moreover, as shown in FIG. 4, the tool holder H ₁ (FIG. 2A) of the embodiment of FIG. 2b, and a solid tool in which the shank and chuck are manufactured from one bar material in the outer shape of the tool holder H ₁ The holder H ₂ (FIG. (B)), the same weight as the tool holder H _1, and the tool holder H ₃ (FIG. (C)) of the frustoconical solid chuck with the shank of HSK-A125 and the conventional A BT50 type tool holder H ₄ (FIG. 4D) was also produced. The holder length L of each of the tool holders H ₁ , H ₂ , H ₃ , and H ₄ was set to three types of 165 mm, 225 mm, and 285 mm.

When the cutting tool A is shrink-fitted into the tool holders H _{1 to} H ₄ and a horizontal load N of 100 kg is applied to the tip of the cutting tool A, the bending of the cutting tool tip in the horizontal direction (the solid line in each figure) (Movement length from chain to chain line). At this time, the protruding amount of the cutting tool A from the tool holder (the tip of the chuck portion 30) was set to three times the cutting tool diameter (= e). In each tool holder _H 1 to H _4, represent a mass (kg) Comparative Table 3, the table 4 shows a comparison of the amount of bending in Table 5 (mm).

From this test result, in comparison (H ₁ / H ₂ ) between the tool holder H ₁ according to the present invention and the solid tool holder H ₂ , the tool holder H ₁ has a mass of about 20% from Table 3. The weight can be reduced, and from the comparison of Table 4 (H ₁ / H ₂ ), the decrease in rigidity due to the weight reduction is suppressed to 10% or less.
Further, in comparison with the notch small conventional standard tool holder H _4, from the "H ₁ / H _4" in Table 3, although the mass of both (H _{1, H 4)} is almost equivalent, a comparison of Table 4 The amount of deflection from (H ₄ / H ₁ ) is as large as 1.5 times in the former (H ₄ ).
Furthermore, when comparing with shapes having the same mass, the solid tool holder H ₃ is compared with the tool holder H _{1 from} the comparison (H ₃ / H ₁ ) in Table 5, and the deflection amount is 1.13 to 1.3. It is 65 times larger.
From the above, it can be understood that the intermediate member 20 having a hollow tapered shape as in the configuration of the present invention has an advantage that it can be greatly reduced in weight while preventing a decrease in bending rigidity.

In addition, it can be understood from Tables 3 to 5 that the longer the holder length L, the more prominent the light weight effect can be while preventing a decrease in bending rigidity. For this reason, the holder length L is generally long for large workpieces, and the tool holder with a shank attached to a high torque main shaft such as an HSK shank is used for machining the large workpiece. Therefore, the momentum and the holder length L become longer, and the light weight effect can be effectively obtained.
Further, from other experiments, the diameter f (see FIG. 2a) of the joint surface between the intermediate member 20 and the chuck member 30 is 0.8 or less (f <0) of the diameter c of the joint surface between the intermediate member 20 and the shank member 10. 0.8c), and the thickness (wall thickness) t is preferably 5 to 30 mm.

Since the tool holder of this embodiment includes the shank member 10, the intermediate member 20, and the chuck member 30, the shank member joint side structure, the chuck member joint side structure of the intermediate member 20, and the length of the intermediate member 20 in the axial direction. Various combinations are possible by standardizing the lengths. In addition, the chuck member 30 can be bonded to chuck members suitable for various types of cutting tools by standardizing the bonding diameter (structure) with the cutting tool A.
For example, as shown in FIG. 5, by preparing various types of chuck members 30a, 30b, 30c, 30d, and 30e for intermediate members 20 (20a, 20b, and 20c) of various sizes and shapes, The tool holder can be obtained. In the figure, the shrink-fitting chuck member 30a and the collet chuck member 30b in the figure are connected (joined) to the intermediate member 20a, and the collet chuck member 30c and the cutter chuck are connected to the intermediate member 20b. The member 30d is connected, and the side lock chuck member 30e is connected to the intermediate member 20c. At this time, the intermediate member (extension member) 20 can appropriately select a plurality of sizes in the axial direction and the radial direction depending on the shape of the chuck member 30. One or two or more intermediate members 20 can be combined and the axial direction can be freely changed.
As described above, the chuck of the tool holder is composed of the intermediate member 20 and the chuck member 30, and the intermediate member 20 and the chuck member 30 can be joined to each other and various shapes can be used. The productivity of tool holders to be improved can be increased and the delivery time can be shortened.

  Incidentally, the system of the form shown in FIG. 5 or the like is generally called a modular tool, and is often found in a tool holder for boring. However, this type of conventional modular tool is characterized in that it can be freely attached and detached, and as a connection mechanism, a connection method using screws is mainly used, or a method according thereto is used. For example, the joining of each member described in Patent Document 4 is an intermediate part (extension part) connected by screwing, and this is mainly intended to extend in the axial direction. For this reason, each part (member) is solid (solid) and does not contribute to weight reduction. Also, normally, in heavy cutting with an end mill tool, a tool holder connected in a modular manner by welding joining shown in FIG. 5 is not used.

In the above embodiment, the shank is an HSK-A125 shank. However, the tool holder is not limited to other various kinds of HSK attached to the main shaft to which high torque is applied, for example, HKS-A100, and the tool holder of the HSK shank. not, the tool holder of course to be attached to the spindle of a high torque, such as the tool holder H ₄ above BT50 type, even in a tool holder that is attached to the spindle of less torque, the present invention may be employed.
Further, the shank or the like is not composed of the three members 10, 20, and 30, and the shank and the chuck are manufactured from one bar material as shown in FIG. Of course, the present invention can be applied to a tool holder that is manufactured from one bar material and welded to the shank member 10.
Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

10 Shank member 11 Manipulator part 20 Intermediate member (extension part)
30 chuck member A cutting tool _{H 1, H 2, H 3} , H 4 toolholder

Claims (4)

A tool holder mounted on the main shaft of a machine tool with the shank provided with a chuck whose outer peripheral surface is gradually reduced in diameter toward the tip of the shank,
A shank portion constituting the shank having a manipulator portion (11), a chuck portion constituting a chuck portion for holding a cutting tool of the chuck, and a remaining portion of the chuck constituting between the shank portion and the chuck portion. A taper that consists of a hollow intermediate portion, and the outer peripheral surface of the intermediate portion and the outer peripheral surface of the chuck portion are gradually reduced in diameter toward the tip of the chuck in order to reduce the maximum tool moment, inertia moment, and inertia force. And the hollow inner peripheral surface of the intermediate portion is shaped along the outer peripheral surface,
A tool holder characterized in that the thickness (t) between the outer peripheral surface and the inner peripheral surface of the intermediate portion is gradually increased from the chuck portion side toward the shank portion side. The shank part, the intermediate part, and the chuck part are composed of a shank member (10), an intermediate member (20), and a chuck member (30), which are separate members, respectively, and the shank member (10) , the intermediate member (20), and The tool holder according to claim 1, wherein the intermediate member (20) and the chuck member (30) are joined to each other through a welded portion . The shank is an HSK shank, and when the cutting tool (A) is mounted, the cutting tool (A) is mounted on the chuck portion by shrink fitting. The tool holder according to 2. The tool holder according to any one of claims 1 to 3, further comprising a cured layer on the inner and outer peripheral surfaces of the intermediate portion.

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